Transport mechanism for an automated integrated circuit handler

ABSTRACT

A transport mechanism for an automated integrated circuit handler comprises a belt having a plurality of pockets thereon. Each pocket is adapted to carry a single integrated circuit therein and is also adapted for the automatic injection or integrated circuits thereinto and ejection of integrated circuits therefrom. None of the transport functions is gravity-driven. In addition, each pocket has slots therein which allow a test apparatus access to the leads of each part for electrical testing. The belt carries the pockets sequentially past a loading station at which parts are injected, a test station at which testing takes place and at least one output location at which parts are ejected. A high throughput integrated circuit handler capable of handling 60,000 parts per hour or more can be achieved with the disclosed transport mechanism.

FIELD OF THE INVENTION

The present invention relates, in general, to a transport mechanismuseful in an automated integrated circuit handler. More particularly,the invention relates to a mechanism for transporting integratedcircuits from an input station past a test station and to a sortingstation, which mechanism is suitable for use in a high-throughputautomated integrated circuit handler.

BACKGROUND OF THE INVENTION

Automated integrated circuit handlers are almost universallygravity-driven in at least some portion of the mechanism responsible formoving integrated circuits about. Because this puts a fundamental upperlimit on the acceleration which can be applied to move a part, it alsoplaces limits on achievable throughput.

The basic function of an integrated circuit handler is to acceptintegrated circuits at an input location, move them to and past astation at which some activity takes place, such as a test station, andon to an output location of some kind. In many cases these functions maybe embellished, but these functions are universal to integrated circuithandlers.

In addition to a high throughput capability, a transport mechanism foran integrated circuit handler should be as simple as possible in orderto achieve high reliability. The design should preferably allow for easyreplacement of component parts and for modification to account fordiffering integrated circuit packages.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide animproved transport mechanism for an integrated circuit handler.

A further object of the present invention is to provide a highthroughput, reliable and modifiable transport mechanism for anintegrated circuit handler.

These and other object and advantages of the present invention areprovided by a conveyor system comprising a toothed belt and a pluralityof integrated circuit carriers, or pockets, which are removably attachedto the belt. Each pocket is adapted to carry one integrated circuit. Oneend of each pocket has an opening which allows passage of parts into andout of the pocket. As the belt is driven around a circuit defined by apair of pulleys, the pockets are successively carried past an inputstation at which integrated circuits are injected into the pockets, atest station at which an electrical test is performed on each integratedcircuit, and finally an output/sorting station at which integratedcircuits are ejected from the pockets according to sort categoriesdefined by the tester apparatus.

These and other objects and advantages of the present invention will beapparent to one skilled in the art from the detailed description belowtaken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a small outline integratedcircuit (SOIC) part, a sleeve for holding a plurality of such parts andan end cap for such a sleeve according to one aspect of the presentinvention.

FIGS. 2A, 2B and 2C are front, top and end views, respectively, of ahigh speed integrated circuit handler according to the principles of thepresent invention.

FIGS. 3A, 3B, 3C, and 3D are top, side and two detail views,respectively, of an automated integrated circuit sleeve handleraccording to one aspect of the present invention.

FIGS. 4A and 4B are a cross-sectional view and an end view,respectively, of a pusher mechanism according to one aspect of thepresent invention for use at the sleeve unloader station of the sleevehandler of FIGS. 3A-3D.

FIGS. 5A and 5B are end and cross-sectional views, respectively, of aninput buffer track and pocket loader mechanism according to one aspectof the present invention.

FIGS. 6A, 6B, 6C and 6D are top, side and two detail views,respectively, of a continuous belt and pocket transport arrangementaccording to one aspect of the present invention.

FIGS. 7A and 7B are top and cross-sectional views, respectively, of apocket unloader mechanism according to one aspect of the presentinvention.

FIGS. 8A, 8B, 8C and 8D are top, end, cross-sectional and detail views,respectively, of an output buffer track according to one aspect of thepresent invention.

FIG. 9 is a schematic diagram of an electrical control structure of thehigh speed integrated circuit handler according to the principles of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates, in perspective, a typical integrated circuit 10 andsleeve 13 therefore and an end cap 15 for the sleeve according to oneaspect of the present invention. The ensuing description of the presentinvention will refer to the type of IC package illustrated here, whichis referred to as a small outline integrated circuit (SOIC). Of course,many different packages exist and would be equally well suited tohandling with the concepts discussed with obvious modifications thereto.Part 10 generally comprises a body 12 and a plurality of leads 11extending therefrom. In the case of an SOIC package as illustrated,leads 11 extend below the bottom of body 12 and are formed so as to endparallel to a surface to which they will be mounted, such as a circuitboard. To provide reliable, automated mounting of such components, thetolerance of the lead placements must be extremely small, which requiresthat no malformation of the leads occur during handling of the parts atfinal test.

Sleeve 13 generally comprises an elongated hollow tube of plastic havinga generally A-shaped cross-section, as shown. In addition, a hole 14 inthe upper surface of sleeve 13 a short distance from the end thereofacts to engage a catch on end cap 15. In the case of SOIC's, sleeve 13is approximately 19 inches long and holds either 47 or 96 parts,depending on the number of leads, or the overall length, of each part.

End cap 15 comprises a body 16 which is dimensioned to fit within sleeve13, an end flange 17 which fits over the end of sleeve 13, a catch 18protruding from the upper side of body 16 which engages hole 14 insleeve 13 to retain end cap 15 therein and a passage 19 extendingthrough end flange 17 and body 16. Passage 19 is dimensioned to allowpassage of a pusher mechanism therethrough to contact the SOIC's withinsleeve 13, but not to allow the SOIC's to escape. The end of passage 19at end flange 17 is preferrably chamfered, as shown, to ease insertionof the pusher mechanism (see FIGS. 4A and 4B). In addition to the catcharrangement shown, other arrangments, such as friction fit, may be usedto secure end cap 15 within sleeve 13.

FIGS. 2A-2C illustrate, in front, top and side views, respectively, ahigh speed integrated circuit handler according to the principles of thepresent invention. Because of the complexity of the handler, somedetails are omitted from FIGS. 2A-2C, but are shown in later Figures.The major portions of the handler are an automated sleeve handlerapparatus 23, a sleeve unloader apparatus 24, an input buffer track 25,a pocket loading apparatus 26, a continuous belt transport system 27with associated drive motor 28, a test area 29, a pocket unloadermechanism 30, a plurality of output buffer tracks 31 with associatedsleeve loading stations 32 in sleeve handler 23 and output bins 33.

The operation of the illustrated integrated circuit handler is begun bythe manual loading of a relatively large number of sleeves containinguntested parts into input hopper portion 34 of sleeve handler 23. Thesleeves must all be aligned with their long axes parallel, but nofurther manual alignment is required. Sleeve handler 23 singulates thesleeves, uniformly orients them and presents each sleeve at a sleeveunloader station 35. Sleeve unloader 24 then operates to push the partsout of the sleeve and onto input buffer track 25. The empty sleeves aremoved to buffer portion 36 of sleeve handler 23 to wait until needed atsleeve loading stations 32.

Once on input buffer track 25, the parts are moved toward pocket loadermechanism 26. Continuous belt transport system 27 carries a plurality ofpockets (not shown) which are each adapted to hold exactly one part. Astransport 27 is indexed to bring an empty pocket in alignment withpocket loader mechanism 26, the latter is operated to inject one partfrom input buffer track 25 into the empty pocket. As transport 27 isfurther advanced, each pocket, now carrying a part, is brought into testarea 29, wherein a test head (not shown) including test leads (also notshown) makes electrical contact to the leads of the part. As contact ismade, transport 27 is halted for a period of time sufficient for anexternal test system to perform electrical tests on the part and assignthe part to one of the up to six output categories.

Transport system 27 is further advanced, with a part being tested ateach stop. Eventually, each pocket reaches pocket unloader mechanism 30.When the pocket bearing a particular part is aligned with the correctone of the six output buffer tracks 31, pocket unloader mechanism 30 isoperated to eject that part from the pocket onto the output buffertrack. The system controlling the handler keeps a count of the number ofparts which have been assigned to each output category in order that anempty sleeve in buffer portion 36 of sleeve handler may be positioned inalignment with sleeve loading stations 32 in anticipation of aparticular output buffer track being full. In fact, each output buffertrack is long enough to hold slightly more than one sleeve-full of partsso that parts may continue to be loaded onto a track while other partsare being unloaded therefrom into an empty sleeve.

When one of output buffer tracks 31 contains a sleeve-full of parts andan empty sleeve has been aligned with that track at sleeve loadingstation 32, the track is operated to slide the parts into the sleeve.During subsequent movements of sleeve handler 23, this full sleeve iseventually brought into alignment with the output bin 33 which isappropriate for the parts in that sleeve. A "trapdoor" mechanism (notshown) is then operated to drop the sleeve into the bin for manualremoval by an operator.

The entire system just described is designed to provide a throughput ofapproximately 60,000 parts per hour, or one part every 60 milliseconds.A test time of approximately 30 milliseconds per part is assumed. Thus,the handler must be capable of indexing from one part to the next at thetest head in approximately 30 milliseconds. As is apparent, this figureof merit can be carried through the entire handler to calculate thethroughput rate of any portion thereof. In no case is any previouslyknown handler capable of achieving the desired throughput rates.

As will be apparent to one skilled in the art, many details have beenomitted from the functional description above. Most of these will bediscussed in detail below. Some, such as the detailed structure andoperation of the electrical test apparatus, are beyond the scope of thepresent invention.

Referring now to FIGS. 3A-3D, sleeve handler 23 is described in detail.The sides of sleeve handler 23 are defined by a pair of parallel sidewalls 44 which are spaced so that a sleeve just fits lengthwise betweenthem. This is because sleeves loaded into handler 23 will have only oneend cap, with the other end being open to allow removal and reloading ofparts. Walls 44 serve to hold the parts in the sleeves during handling.

The structure and function of sleeve handler 23 is most easilyunderstood as comprising five major functional units or portions. Aninput hopper portion 34 serves to receive a plurality of sleeves,singulate them and present partially oriented single sleeves to the nextportion. An orientation and sleeve unloading portion 48 receives single,partially oriented sleeves from input hopper portion 34, uniformlyorients the sleeves and presents them to an unloading station 35. Afterthe parts are ejected from the sleeve by sleeve unloader 24, the emptysleeves are passed to an empty sleeve buffer portion 36. When thehandler system controller anticipates the need for an empty sleeve atone of the six sleeve loading stations 32, an empty sleeve is passedfrom buffer portion 36 to a sleeve loading portion 50. Sleeve loadingportion 50 presents the sleeve in alignment with the appropriate outputbuffer track (not shown) for loading. Subsequently, the filled sleevesare passed to a sleeve binning portion 51 for output into an appropriatebin.

Input hopper portion 34 of sleeve handler 23 comprises a first hopperwall 45 and a second hopper wall 46 which extend between sleeve handlerwalls 44 and define the input hopper. That is, sleeves are loaded intothe handler between hopper walls 45 and 46. The bottom of the inputhopper is defined by a main input belt 53 having a plurality of paddles55 thereon and a first alignment belt 54 having a plurality of paddles56 thereon. Both belts 53 and 54 are continuous, preferably molded beltswhich are carried on pulleys which, in turn, are fixed to axlesextending between sleeve handler walls 44. For reasons discussed below,paddles 55 and 56 have a relatively complex cross-section and may,therefore, be somewhat expensive to acquire. It may be preferrable tomold or machine the paddles separate from the belts and affix them bymeans of clips or the like. Main input belt 53 is carried on pulleysfixed to a first axle 58, a second axle 60, a third axle 61 and a fourthaxle 62. First alignment belt 54 is carried on pulleys fixed to firstaxle 58 and second axle 60. As is apparent, the relative placement ofpaddles 55 and 56 and may be adjusted by adjustment of the appropriatepulleys on axles 58 and 60. Both main input belt 53 and first alignmentbelt 54 are driven by a first motor 59 which drives first axle 58.

As is most clearly apparent from FIG. 3A, main input belt 53 is actuallya pair of belts with wide paddles extending therebetween. As is alsoapparent, alignment belt 54 is, in fact, two belts which lie between theoutside edges of main input belt 53 and walls 44. Between first axle 58and second axle 60, main input belt 53 and alignment belts 54 aresubstantially parallel along the bottom of the input hopper.

Referring to the detailed view of FIG. 3C, the structure and function ofbelts 53 and 54 are described. In the cross-section of this figure,belts 53 and 54 appear coincident. In addition, paddles 55 on belt 54and paddles 56 on belt 54 are seen to be aligned in order to define aspace 57. Space 57 is defined at its back edge by the front of a mainbelt paddle 55, at its bottom side by belts 53 and 54 and at its frontedge by the back of an alignment belt paddle 56. The shape of space 57thus defined is chosen so that a sleeve must be in one of twoorientations about its longitudinal axis in order to fall into space 57.In both orientations, the sleeve may be described as lying on its sideagainst belts 53 and 54. The two orientations are related by a 180degree rotation about the longitudinal axis. In addition, space 57 isdefined so that only one sleeve may reside therein. Thus, the functionof belts 53 and 54 is to singulate the sleeves and to partially orientthem.

As sleeves are carried toward the upper end of input hopper portion 34,belts 53 and 54 pass immediately under a pair of rollers 63 and 64.Roller 63, which is driven by a second motor 68 and extends betweensleeve handler walls 44 immediately under input hopper wall 46, servesto ensure that no sleeves are carried out of the input hopper atoppaddles 55 and 56 by knocking any such sleeves back into the inputhopper. Roller 64, which is also driven by second motor 68 through gearsattached to roller 63, extends just far enough inside sleeve handlerwall 44 to engage the ends of passing sleeves and contacts sleeves inthe region subsequent to second axle 60. In this region, the sleeves areno longer confined in the restrictive space 57 and may be manipulated.Roller 64 does just this by knocking the sleeves down so that they restflat on main input belt 53 between paddles 55. Once again, there are twopossible orientations which the sleeves may take which are related by a180 degree rotation about the long axis.

By the time the sleeves have been carried past rollers 63 and 64, theyhave passed under input hopper wall 46 and are within orientation andunloading portion 48 of sleeve handler 23. An orientation apparatus 65is mounted in one side wall 44 in order to engage the end of eachsleeve. Orientation apparatus 65 is positioned to engage the sleeveswhile they are being carried only by main input belt 53, the paddles 55of which are so spaced as to allow rotation of sleeves carriedtherebetween.

FIG. 3D is a detailed cross-sectional view of orientation apparatus 65taken along the line 3D of FIG. 3A. Apparatus 65 is basically a slottedrod which is adapted to receive the end of each sleeve therein as itpasses the location of apparatus 65. Immediately preceding apparatus 65is a sensor 67 attached to handler wall 44, which determines which ofthe two possible orientation each sleeve is in. In the embodimentillustrated, sensor 67 comprises a switch having a actuator button 69.When a sleeve is upside-down, as illustrated, button 69 falls into thespace between the legs of the "A" and switch 67 is not actuated. In theother orientation, button 69 will be depressed by the top of the sleeveand actuate switch 67. If the sleeve is in the orientation illustratedin FIG. 3D, the slotted rod is rotated 180 degrees by means of thirdmotor 66 (FIG. 3B). Since the end of the sleeve is within the slot, thisalso rotates the entire sleeve. Obviously, if the sleeve is already inthe proper orientation, orientation apparatus 65 is not operated. Thus,sleeves leaving the location of orientation apparatus 65 are uniformlyoriented.

As the sleeves are advanced further by movement of main input belt 53,their ends are engaged by a second pair of alignment belts 70 withpaddles 71. Second alignment belts 70 are carried on pulleys fixed tothird axle 61 and fourth axle 62 and run between the edges of main inputbelt 53 and walls 44. Because the space between paddles 55 of main inputbelt 53 must be great enough to allow orientation of the sleevestherein, the position of those sleeves is not sufficiently precise toallow reliable positioning at unloading station 35. Therefore, paddles71 perform the function of engaging the rear edge of each sleeve andforcing the front edge thereof against the trailing edge of a paddle 55on main input belt 53. This action determines the position of the sleevewith sufficient accuracy to allow reliable unloading.

When each sleeve has advanced to the position indicated by referencenumeral 35, which is referred to as the sleeve unloading station,unloader mechanism 24 (not shown in FIG. 3B) is operated to push theparts out of the sleeve. A wall 86 (not shown in FIG. 3A) extends overthe sleeves once they are past orientation apparatus 65 and extends tooutput portion 51 to improve alignment and stability of the sleeves.This is described in detail below with reference to FIGS. 4A and 4B.

As main input belt 53 and second alignment belt 70 are advanced further,each sleeve is moved past unloading station 35 until its ends aresupported by a pair of buffer belts 72. Buffer belts 72 are carried bypulleys which are carried by fourth axle 62, a fifth axle 73 and a sixthaxle 74. The buffer belt pulleys which are carried by fourth axle 62 andfifth axle 73 are not fixed thereto, but turn freely thereon. The bufferbelt pulley which is carried by sixth axle 74 is fixed thereto. Bufferbelts 72 run immediately adjacent to walls 44. Sixth pulley 74 is drivenby a fourth motor 75.

Buffer belts 72, which comprise empty sleeve buffer portion 36 of sleevehandler 23, are smooth in order that empty sleeves may slide thereon. Astop mechanism 76 located near the end of buffer belts 72 which isfurthest removed from unloading station 35 serves to prevent emptysleeves from exiting buffer portion 36 until they are needed at a sleeveloading station 32. In the illustrated embodiment, stop mechanism 76comprises a simple rocker arm arrangement which operates similarly tothe anchor level of a watch escapement mechanism. Stop mechanism 76 ispreferably solenoid-driven. Of course, many modifications to thisarrangement are possible. As will be apparent to one skilled in the art,buffer portion 36 need not be particularly large, since the rate of useof empty sleeves will be steady after an initial period during which thehandler fills with parts. In the preferred embodiment, buffer portion 36will hold approximately 10 sleeves.

The system controller, which maintains a count of the number of partsbeing assigned to each of the six output categories, is able toanticipate which output buffer track 31 (FIG. 2B) will be the next toneed unloading. When such a need is anticipated, stop mechanism 76 isoperated to release one empty sleeve from buffer belts 72.

When an empty sleeve is so released, the motion of buffer belts 72 movesit into position to be engaged by a pair of main output belts 77 havingpaddles 78 and a pair of output alignment belts 79 having paddles 80.Each sleeve is held between a paddle 78 of belt 77 and a paddle 80 ofbelt 79. As before, the purpose of the double belt arrangement is toprovide adequate alignment of the sleeves, in this case so that they areproperly aligned with the output buffer tracks for loading. Main outputbelts 77 are carried on pulleys fixed to fifth axle 73, a seventh axle81, a ninth axle 84 and a tenth axle 85. Seventh axle 81 is driven by afifth motor 82. Output alignment belts 79 are carried by pulleys fixedto fifth axle 73, seventh axle 81 and an eighth axle 83.

An alternate method of operation is to maintain an empty sleeve inalignment with the first sleeve loading station (the one closest tobuffer belts 72. Typically, this station would be used for binningwhatever category of parts is expected to receive the most parts. Thisscheme would reduce the amount of time necessary to index an emptysleeve into position to be filled.

As main output belts 77 and output alignment belts 79 pass over seventhaxle 81, output alignment belts 79 separate and the sleeves are heldonly loosely between paddles 78 of main output belt 77. At this point,wall 86, which extends between sleeve handler walls 44, retains thesleeves against main output belts 77. As main output belts 77 pass overninth axle 84, they pass into sleeve binning portion 51 of sleevehandler 23.

Sleeve binning portion 51 comprises up to six output bins 33, aretaining ridge 87, up to six doors 88 in retaining ridge 87 and up tosix door actuators 89 associated therewith. Retaining ridge 87 runsalong the inside of sleeve handler wall 44 and serves to maintain thefull sleeves against main output belt 77 until the sleeve is over theappropriate bin 33. At this point, the appropriate door actuator 89 istriggered to open its associated door 88 and thus drop the sleeve intobin 33 for removal by the operator.

A plurality of belt tensioners 90 are appropriately distributedthroughout sleeve handler 23 for maintenance of tension on the variousbelts therein.

Referring now to FIGS. 4A and 4B, the structure and operation of sleeveunloader mechanism 24 is described in detail. A first tape guide 94extends between sleeve handler walls 44 several inches below sleeveunloading station 35. First guide 94 is a hollow housing adapted toretain therein a metal tape 98. Tape 98 is preferably very similar indesign and construction to the steel tape used in a housheoldretractable tape measure. In fact, just such a tape has been usedsuccessfully. In this example, the leading end of tape 98 (the end whichcontacts the parts) was approximately doubled in thickness to improvethe contact between the tape and the parts and to prevent the tape from"overriding" the parts.

Mounted on first guide 94 are a first tape sensor 95 and a second tapesensor 96. Each sensor is preferably a simple light source and sensordisposed on opposite sides of guide 94 so that tape 98 interrupts thelight between the source and the sensor. In this manner, the position oftape 98 can be sensed.

Immediately adjacent the end of first guide 94 and outside sleevehandler wall 44 is a tape drive mechanism comprising a tape drive wheel97, a drive motor 99 coupled thereto to rotate wheel 97, a first idlerwheel 101 and a second idler wheel 102. Tape 98 passes out of firstguide 94 and approximately 180 degrees around drive wheel 97. Idlerwheels 101 and 102 serve to maintain tape 98 in close contact with drivewheel 97. By appropriate operation of drive motor 99, tape 98 can bevery rapidly moved into and out of sleeve positioned at sleeve unloadingstation 35.

In its normal, or unextended, position, tape 98 continues past drivewheel 97 and into a second guide 100, but stops just short of passingback into the space between sleeve handler walls 44. When a sleeve isproperly positioned at sleeve unloading station 35, the passage in theend cap thereof (see FIG. 1) is precisely aligned with the opening ofsecond tape guide 100. Thus, when tape 98 is advanced, it will passthrough the end cap (see FIG. 1) of the sleeve at unloading station 35,make contact with the first part therein and force the parts out theother, uncapped end of the sleeve.

The normal position of tape 98 is unextended. In this position, tape 98interrupts both sensor 95 and sensor 96. When a sleeve is in position tobe unloaded, motor 99 is activated and tape 98 is moved until itstrailing end first passes sensor 95 and eventually passes sensor 96. Thesignal from sensor 96 indicates that tape 98 is in its fully extendedposition and that all of the parts have been ejected from the sleeve. Atthis point, before the end of tape 98 leaves first guide 94, thedirection of motor 99 is reversed. When the signal from sensor 95 onceagain indicates that tape 98 is in its unextended position, motor 99 isstopped.

As will be apparent to one skilled in the art, the basic mechanism ofsleeve unloader 24 could readily be modified to serve a sleeve loadingfunction. In other words, pusher tape 98 would push a sleeve-full ofparts from a buffer track or the like into a properly aligned, emptysleeve.

The sleeve handler and unloader discussed above must be capable ofpresenting full sleeves and unloading them quickly in order to meet thehigh throughput targets required for economical operation. It isbelieved that, utilizing the concepts described, it is possible tounload approximately one sleeve per second. Approximately one-halfsecond is required to push all of the parts out of the sleeve.Approximately 100 milliseconds are required to bring tape 98 back to itsstarting position. Approximately 400 milliseconds are required for thesleeve handler to position a new sleeve for unloading. With at least 47parts per sleeve, this throughput rate exceeds that necessary tomaintain an overall throughput rate of 60,000 parts per hour.

FIGS. 5A and 5B illustrate input buffer track 25. FIG. 5A is an end viewof track 25 as seen from the input end; that is, the end which isaligned with sleeve unloading station 35 (FIG. 2B). A body portion 103of track 25 comprises a central slot 104 running the length thereof, apair of rails 105a and 105b immediately adjacent slot 104 and parallelthereto and a pair of lead spaces 106a and 106b immediately adjacentrails 105a and 105b, respectively. A part (shown in phantom) may besupported on rails 105a and 105b while the leads thereof lie within leadspaces 106a and 106b. Thus, no potentially damaging contact is made withthe leads.

A pair of cap members 107a and 107b are mounted to base member 103 asshown. The inner and lower edges of cap member 107a and 107b are adaptedto engage the upper edges of the part and so to maintain the part inalignment down track 25. A space 111 between cap members 107a and 107bis provided to allow visual monitoring of parts within track 25 andmanual adjustment of jammed parts and the like.

A pulley 108 lies within slot 104 and is carried on an axle 109extending through body portion 103. A smooth belt 112 is carried onpulley 108 and is adjusted so as to make contact with the bottom of eachpart in the space between rails 105a and 105b. Belt 112 provides themotive force to propel parts down track 25. A motor 110 mounted to bodyportion 103 is attached to axle 109 and drives pulley 108 thereby.

Referring back, for a moment, to FIG. 2B, a sensor mounted in baseportion 103 of track 25 at the location of line 113 senses when there isroom in track 25 for a sleeve-full of parts. This triggers the unloadingof the next sleeve at sleeve unloading station 35. The sensor may simplycomprise a light source and detector disposed on opposite sides of bodyportion 103 so that the lack of a part therebetween provides a signal.The sensor is positioned slightly more than one sleeve length,approximately 19 inches, from the input end of track 25.

Referring now to FIG. 5B, pocket loading mechanism 26 is shown incross-section. This is, of course, located at the output end of inputbuffer track 25. At this end, an idler pulley 114 carries belt 112 inslot 104 of body portion 103. Cap member 107a ends somewhat short of theend of track 25 and is replaced in function by an end cap 115. A pocket116, which has a space 117 therein adapted to receive and hold a singlepart, is aligned with the end of track 25 between end cap 115 and bodyportion 103. As belt 112 passes over idler pulley 114, parts are removedfrom belt 112 and forced between a tongue portion 121 of body portion103 and an injector wheel 119. Injector wheel 119 and tongue 121 arespaced so that a part just fits between them. Injector wheel 119 isadvanced in the direction of rotation indicated by a motor 125 (see FIG.2B) until a part occludes a light source-detector arrangement at theposition indicated as 120.

Once a part is in position lodged between injector wheel 119 and tongue121, the rotation of wheel 119 is halted until the system controllerindicates that an empty pocket 116 is in position to receive the part.While injector wheel 119 is halted, parts simply back up down track 25.Normally, belt 112 is driven so as to present parts to injector wheel119 just about as fast as they are needed. However, immediately afterthe loading of a new sleeve of parts onto track 25, there may be a gapbetween the parts. In this case, belt 112 is momentarily speeded up toclose this gap.

When an empty pocket 116 is in position to receive a part, injectorwheel 119 is spun rapidly in the direction indicated. Thissimultaneously shoots a part into pocket 116 and brings a new part intoposition between injector wheel 119 and tongue 121. A lightsource-detector arrangment 123 "looks" through a hole 122 in the back ofpocket 116 to determine that the part has been successfully loaded. Ifthe part has jammed at the mouth of pocket 116, both sensors 120 and 123will so indicate, since the part will not clear sensor 120 and will notreach hole 122. In this case, injector wheel 119 is backed up foranother try. A vacuum tube 124 extends through a wall 118 against whichpocket 116 is being forced. The suction thus provided through space 117of pocket 116 assists in locating the part completely inside pocket 116.

Referring now to FIGS. 6A and 6B, continuous belt transport system 27 isillustrated. FIG. 6A is a top view of system 27 with the pocket loaderand unloader mechanisms removed for clarity. A first transport systemwall 128 and a second transport system wall 129 provide a frame forsystem 27. At one end thereof, a drive motor 28 is mounted to first wall128. Drive motor 28 is coupled to a pulley which is not visible in thisview and which turns the transport belt. The belt is also not seen inthis view because it is covered by a plurality of pockets 130, each ofwhich is carrying an individual part and each of which has a pluralityof slits 131 in the upper surface thereof through which electricalcontact is made to the leads of the parts. Nearly all of the top surfaceof system 27 is available as test area 29. However, as is apparent, onlya relatively small portion of test area 29 is actually utilized for thispurpose. Typically, a load board containing interface circuits and thelike is located in test area 29 so as to be physically and electricallyvery close to the actual test sight and may require significant portionsof test area 29.

FIG. 6B is a side view of second transport system wall 129 as seen froma perspective between walls 128 and 129. The dotted lines indicate thepath of the transport system belt and the arrows indicate its directionof motion. The outer and inner edges of the pockets are defined by thetwo dotted lines. A first hole 132 in wall 129 allows input buffer track25 (see FIG. 2B) to contact the belt and pockets. A second hole 136similarly provides access to output buffer tracks 31 (FIG. 2B). Bothfirst hole 132 and second hole 136 are located along the lowerhorizontal portion of the path of the belt. Located along the upperhorizontal portion of that path are a first guide member 133 and asecond guide member 134. Guide members 133 and 134 engage the inner andouter edges, respectively, of each pocket as it passes a test sight 137.Guide members 133 and 134 serve to precisely determine the verticalposition of each pocket so that reliable contact may be achieved to theleads of the part. Since the part also has some horizontal freedom ofmovement within its pocket, an alignment spring 135 positioned betweenguide members 133 and 134 engages the end of each part and forces it tothe back of its pocket, thus precisely determining its horizontalposition.

FIGS. 6C and 6D illustrate in detail the pocket/belt arrangement used inthe transport system. Belt 140 is a common, molded, toothed belt of thetype typically used as a timing belt or the like. A pocket 130 isattached to belt 140 by means of a pair of tabs 141 which extend aroundthe edges of belt 140 in the space between two adjacent teeth thereof.This arrangement provides flexibility to make changes in the design ofpocket 130 and also allows the replacement of individual pockets as theywear. In some cases, in which the alignment of each pocket 130 withpocket loading mechanism 26 (FIG. 5B) is particularly critical, it maybe desired to more accurately fix the position of each pocket 130 onbelt 140. A "bump" molded onto belt 140 and a corresponding depressionon the mating surface of pocket 130 may serve this function. In theextreme case, pocket 130 may be molded as a part of belt 140.

Pocket 130 is a custom-molded part of some complexity. Pocket 130 may bedescribed as having an input face 142, an opposite, generally closedface 143, a back side 144 adjacent belt 140 and a contact face 145opposite thereto. Input face 142 has an opening 146 therein which isadapted to receive a part therethrough. The edges of opening 146 arepreferably chamfered, as shown. A pocket space 117 lies within pocket130. Pocket space 117 is adapted to receive and hold a single part andand opening 146 provides ingress and egress to and from pocket space117. A second opening 147 disposed in opposite face 143 is too small toallow ingress and egress of the part, but is useful in the pocketloading and unloading operations (see FIGS. 5B and 7B). A horizontalslot 148 extends through pocket 130 from input face 142 toward oppositeface 143. Horizontal slot 148 allows alignment spring 135 (FIG. 6B) tomake contact with a part in pocket space 117 and force it back against astop 149, which prevents further movement toward opposite face 143.

A plurality of contact slots 131 are disposed on contact face 145 ofpocket 130 and communicate with pocket space 117. Contact slots 131 arelocated so as to match the locations of the leads of a part which is atthe back of pocket space 117 against stop 149. It should be noted thatpocket 130 is carried on the outside surface of belt 140 (see FIG. 6B)so that, at the test station, pocket slots 131 are facing upward ratherthan downward as illustrated here. At least two methods of makingcontact with the leads of the part at the test station are possible withthis arrangement. Preferably, a set of spring-biased test leads ride inslots 131 and make contact with the part leads as each pocket is indexedto a position under the test station. As the belt is indexed, the testleads simply slide over part leads and pocket surfaces beneath them. Analternate method, which is more complex mechanically, is to place thetest leads somewhat above the normal position of pocket 130 so that nocontact is made while belt 140 is indexed. A solenoid or other meanscould be employed to raise each pocket 130 so as to make contact oncebelt 140 has stopped. Such a scheme may be most appropriate for partswith leads on all four sides.

As is apparent to one of skill in the art, the design of pocket 130 ishighly dependent on the particular part for which it is designed.Therefore, the pocket design illustrated here is subject to widevariation.

Referring now to FIGS. 7A and 7B, the structure and function of pocketunloader mechanism 30 is described. Pocket unloader mechanism 30 servesboth to remove the tested parts from the pockets and to sort the partsinto the six possible output categories. A guide block 161 liesimmediately adjacent to the pocket-carrying transport belt (not shown)and has six guide slots 162a-162f therein. Guide slots 162a-162f arespaced one pocket-width apart. As is apparent from FIG. 7B, guide slots162a is aligned with one of the six output buffer tracks 175a, as is thecase with each of the guide slots 162b-162f and output buffer tracks175b-175f (not shown).

A pair of frame members 163 and 164 serve as mounting means for motors165a-165c and 165d-165f, respectively. Six disks 166a-166f are mountedon the spindles of motors 165a-165f, respectively. Six flexible pushrods 167a-167f each have one end mounted eccentrically to disks166a-166f respectively. When motors 165a-165f are in the positionsindicated in FIG. 7A, each flexible push rod 167a167f extends throughits appropriate guide slot 162a-162f, respectively, just to the outeredge of guide block 161.

When the handler is running at a rate of 60,000 parts per hour, pocketunloader mechanism 30 must be capable of ejecting a part and returningto its home position in approximately 30 milliseconds; that is, the timeduring which transport apparatus 27 is stopped. This speed may only beachieved with the extremely low mass mechanism described. The use of aflexible push rod made of nylon or a similar material eccentricallymounted to a disk rotated by a DC servomotor eliminates much mechanicalcomplexity and, therefore, mass.

FIG. 7B illustrates the unloading action. When a pocket 130 carrying apart 169 has been properly positioned in alignment with the appropriateoutput buffer track, in this case track 175a, motor 165a is rotated 180degrees, thus rotating disk 166a and forcing flexible push rod 167athrough guide block 161. Push rod 167a enters pocket 130, contacts part169 and forces it out of pocket 130 and onto track 175a, as shown. Theunloading action is then completed by rotating motor 165a by 180 degreesagain, thus placing the entire apparatus back into its rest position andallowing the advancement of the pocket-carrying transport belt into itsnext position.

Referring now to FIGS. 8A-8D, the output buffer track system isexplained in detail. In the preferred embodiment, six output buffertracks 175a-175f are provided, thus providing six possible outputcategories into which the tester may place the parts. A body portion 176forms the base for each of the six tracks 175a-175f. Six slots 177a-177fin body portion 176 run the length thereof, are parallel to one anotherand are located on the same center lines as are tracks 175a-175f. Sixbelts 178a-178f run in slots 177a-177f, respectively.

Six motors 179a-179f are mounted to body portion 176 along the edgesthereof and drive six drive pulleys 180a-180f, respectively. Belts178a-178f are driven by drive pulleys 180a-180f, respectively.

The detailed construction of tracks 175a-175f is described withreference to FIG. 8D, which is an enlarged end view of the indicatedportion of FIG. 8B. As will be apparent, each output buffer track175a-175f is identical in construction to input buffer track 25.Immediately adjacent slot 177a and running parallel thereto are a pairof rails 181a. Rails 181a are spaced so as to engage a part 182 (shownin phantom) along the bottom surface thereof without engaging thecontacts, or leads, thereof. Immediately adjacent rails 181a and runningparallel thereto are a pair of lead spaces 183a. The leads of part 182are within lead spaces 183a, thus reducing the possibility of damagethereto. This aspect is particularly important in the case of surfacemount packages such as the SOIC package illustrated here, because thetolerance which must be maintained on lead placements is quite severe.

Seven cap members 184a-184g are mounted to body portion 176 intermediatebetween slots 177a-177f and adjacent the outside edges of slots 177a and177f. As shown in FIG. 8D, cap members 184a and 184b engage the upperedges of the body of part 182 and act to maintain the alignment of part182 on rails 181a. Spaces are left between cap members 184a-184g so thatparts can be visually inspected in the various output tracks, jammedparts can be freed and the overall operation of the output buffer tracksystem can be monitored.

As is apparent from FIGS. 8B and 8D, belts 178a-178f do not actuallymake contact with parts which are supported on rails, such as rails181a. This is the only major difference between the input and outputbuffer tracks and is readily achieved by adjusting the height of thepulleys relative to the slots. The normal motive force which propelsparts down tracks 175a-175f is supplied by flexible push rods 167 (FIGS.7A and 7B) of the pocket unloader mechanism. Rails, such as rails 181a,and cap members 184a-184g are dimensioned so as to allow parts to freelyslide down the tracks formed thereby. FIG. 8C illustrates the means usedto control the movement of parts along track 175f. The same structureand function are present in each of the other tracks. In order tominimize confusion, only those details associated with track 175f areshown in FIG. 8C, with foreground and background matter eliminated.

Belt 178f is carried by drive pulley 180f, by an idler pulley 185 at theinput end of track 175f and by a second idler pulley 186 at the outputend of track 175f. Belt 178f also has first, second, third and fourthpaddles thereon 187f, 188f, 189f and 190f, respectively. Each paddle islong enough to extend up from belt 178f into the space between capmembers 184f and 184g, thus making contact with any part which is intrack 175f. While parts are being loaded, but before track 175f containsa sleeve-full of parts, belt 178f is in the position indicated in FIG.8C. That is, first paddle 187f is within the track near the output endthereof and acts as a barrier to limit movement of parts being loadedfurther down the track. Second paddle 188f, third paddle 189f and fourthpaddle 190f area all outside of the track area when belt 178f is in thisposition and do not engage any parts.

When one sleeve-full of parts is in track 175f, belt 178f is advanceduntil both fourth paddle 190f and third paddle 189f have passed overfirst idler wheel 185 and are within the track area. This also advancesfirst paddle 187f until it is just out of the track area. In thisposition, the sleeve full of parts, now being pushed from behind byfourth paddle 190f, can be held until an empty sleeve is aligned withthe output end of track 175f for loading. In addition, newly unloadedparts can be loaded onto track 175f and will be prevented from furthermovement down the track by third paddle 189f, thus keeping the twogroups of parts separate.

In order to prevent accidental ejection of parts from the output end oftrack 175f without an empty sleeve being present, it is intended thatthe above-described belt movement not be carried out until a sleeve isin position. Alternatively, some low-friction means could be inserted ator near the output end of the tracks to prevent ejection of partstherefrom until they are forced out by a paddle. To load an empty sleevewith parts, belt 178f is advanced rapidly. Fourth paddle 190f forces theparts off of the output end of track 175f and into the empty sleeve.This motion is continued until fourth paddle 190f has just passed out ofthe track area and is in the position of second paddle 188f in FIG. 8C.Third paddle 189f is in the position of first paddle 187f, second paddle188f is in the position of fourth paddle 190f of first paddle 187f is inthe position of third paddle 189f. As is apparent, this position isequivalent to that of FIG. 8C and loading of tested parts behind thirdpaddle 189f can proceed.

A pair of passages 191f and 192f are disposed at the input end andoutput end, respectively of track 175f. Similar passages are providedfor each of the other output buffer tracks, but are not shown. Passages191f and 192f are provided to allow the monitoring of track operation bymeans of light source-detectors pairs placed at opposite ends thereof.At the input end, a part which has jammed partially inside track 175fcan be detected by occlusion of the photocell. At the output end, a partjammed partially inside the sleeve being loaded can be detected. Inaddition, passage 192f at the output end is used to "home" belt 178f atthe start of operations. Belt 178f is rotated and paddles 187f, 188f,189f and 190f occlude the photocell as they pass around pulley 186. Wheneither paddle 188f or paddle 190f has just cleared passage 192f, belt178f is stopped and considered to be in a "home" position.

Referring now to FIG. 9, the electronic control structure of the handlerdescribed above is shown. As is apparent, the control structure ismicroprocessor-based. A primary microprocessor 200 (which includesassociated random access and read-only memory) performs the basiccontrol tasks. Primary MPU 200 receives indications of current systemstatus, demands for new parts at the test station, indications of theoutput category for each tested part and other inputs and producescommands for the various servomotor and solenoid drivers, status outputsto the tester and other outputs.

A primary I/O bus 201 is coupled to primary microprocessor 200 andperforms the familiar functions of communicating addresses, commands anddata among the various devices coupled thereto. In the preferredembodiment, primary microprocessor 200 is one of the 68000 family ofmicroprocessors available from Motorola, Inc. in Austin, Tex. The choiceof microprocessor 200 will largely determine the architecture of bus201.

An operator interface 202 is coupled to primary I/O bus 201. Operatorinterface 202 serves to receive commands from the operator via a controlpanel and to provide system status and function indicators to theoperator, also via the control panel. Examples of typical commands arecommands to start or stop handler operation and to unload a partiallyfull output buffer track after all parts in a batch have been tested.Examples of typical status indicators are a warning of a jammed buffertrack or of a malfunctioning sensor or motor.

A system control interface 203 is also coupled to primary I/O bus 201.The primary function of system control interface 203 is to provide aninterface between primary microprocessor 200 and the test equipmentwhich actually performs the electrical measurements on each part. Thisinterface allows the tester to indicate its readiness to test the nextpart and to indicate the output category for each part, among otherfunctions. In addition, any solenoids which are a part of the handlersystem are controlled through system control interface 203.

A system status receiver 204 is also coupled to primary I/O bus 201.System status receiver 204 receives inputs from each of the sense pointsthroughout the handler. Examples are the sensor associated with theinput buffer track which indicates that the buffer has room for asleeve-full of parts and the sensor associated with the transport systemwhich indicates that a part has been successfully injected into itspocket. System status receiver 204 provides these status indicators inappropriate form to I/O bus 201 for action by primary microprocessor200.

Also coupled to primary I/O bus 201 is a servomotor control subsystem205. Servomotor control subsystem 205 comprises a plurality ofservomotor control boards 206. Each servomotor control board 206 is amicroprocessor-based high-speed servomotor controller capable ofcontrolling the position of a predetermined number of servomotorsaccording to an on-line adaptive closed-loop control algorithm. Anexample of such an algorithm is disclosed in co-pending patentapplication Ser. No. 670,253, filed Nov. 9, 1984, now U.S. Pat. No.4,609,855, and assigned to the assignee of the present invention. In thepreferred embodiment, each servomotor control board 206 is capable ofcontrolling up to four servomotors. Since there are a total of 14servomotors in the handler exclusive of the sleeve handler and the maintransport belt motor (one to drive the input buffer track, one to drivethe pocket loading mechanism, six to drive the pocket unloadingmechanism and six to drive the output buffer tracks), four servomotorcontrol boards 206 are utilized. In addition to receiving positioncommands from primary microprocessor 200, servomotor control boards 206provide position indications for each of the 14 servomotors to primarymicroprocessor 200 via I/O bus 201.

A precision servomotor control board 207 is coupled to I/O bus 201 andis dedicated to controlling the position of the main transport systemmotor. This motor requires dedicated control because it is aheavier-duty motor, it is running a larger percentage of the time and itrequires particularly precise positioning to align the pocket with thetest station leads. Again, in addition to positioning the main drivemotor, controller board 207 provides position indicators to primarymicroprocessor 200.

A sleeve handler subsystem 208 is coupled to I/O bus 201. Sleeve handlersubsystem 208 provides all necessary control and command processing forthe sleeve handler portion of the handler. This subsystem is modular toallow flexibility in the sleeve handler design independent of theprimary system control structure. Sleeve handler subsystem 208 comprisesa subsystem microprocessor 210 with associated random access andread-only memory, a subsystem I/O bus 211, a subsystem status receiver212, and two servomotor control boards 213 and 214.

The structure and function of each of the elements of sleeve handlersubsystem 208 is substantially identical to those of the correspondingelements of the greater control system. Subsystem status receiver 212receives status inputs from the various sensors within the sleevehandler and provides status indicators to subsystem I/O bus 211.Servomotor control boards 213 and 214 are identical to boards 206 anddrive the six motors which comprise the sleeve handler (three belt drivemotors, the orientation motor, the input hopper roller drive motor andthe sleeve unloader motor).

An improved, high-speed integrated circuit handler has been shown anddescribed. The disclosed handler is not gravity-driven in any of itsmany parts and thus avoids the several limitations of such handlers. Thedisclosed handler requires very minimal manual sleeve handling and thusreduces the direct labor component of handling costs. The handler iscapable of at least 60,000 parts per hour throughput with a test time of30 milliseconds per part. This throughput rate is much higher than anyknown prior art integrated circuit handler.

We claim:
 1. A transport mechanism for an automated semiconductor devicehandler comprising:a belt having regularly spaced teeth on one side andbeing smooth on the other side thereof; and a plurality of pocketsremovably attached to said smooth side of each belt, each of saidpockets being adapted to carry a single semiconductor device and havingat least one slot in a face thereof opposite to said smooth side of saidbelt, said slot being adapted to allow contact between a lead of saidsemiconductor device and a test contact at a test location, said pocketscovering the entirety of said smooth side of said belt.
 2. A transportmechanism according to claim 1 wherein:said pockets each have a firstend and a second end, each of said pockets also having an opening insaid first end adapted to allow passage of a semiconductor devicetherethrough.
 3. A transport mechanism according to claim 2 wherein:eachof said pockets has a second opening in a second end thereof adapted toallow passage of a semiconductor device ejector therethrough.
 4. Atransport mechanism according to claim 1 further comprising:at least twopulleys carrying said belt and engaging said side of said belt havingregularly spaced teeth; and means for driving at least one of said atleast two pulleys so as to transport each of said pockets past at leastone input location at which said semiconductor devices are injected intosaid pockets and at least one output location at which saidsemiconductor devices are ejected from said pockets.
 5. A transportmechanism for an automated semiconductor device handler comprising:abelt; pulley means for carrying said belt such that said belt defines aloop; a plurality of pockets carried on said belt, each of said pocketshaving at least one slot therein to allow contact between a lead of asemiconductor device and a test contact, and being adapted to hold asingle semiconductor device; an input station at a first location onsaid loop defined by said belt at which said semiconductor devices areinjected into said pockets; a test station at a second location on saidloop at which an electrical test is performed on said semiconductordevice in said pockets; and an output station at a third location onsaid loop at which said semiconductor devices are ejected from saidpockets.
 6. A transport mechanism according to claim 5 wherein:saidpockets are removably attached to said belt.
 7. A transport mechanismaccording to claim 6 further comprising:means for determining a positionof each of said pockets on said belt.
 8. A transport mechanism accordingto claim 5 wherein:each of said pockets has a first opening in saidfirst end thereof to allow passage of said semiconductor devicetherethrough and a second opening in a second end opposite to said firstend.